1. Field of the Invention
The present invention relates to a device in an actuator for variable adjustment of the pistons of hydraulic slave cylinders for regulation of for example the elevation adjustment of work stations, at which the pistons are actuated by way of a pusher which is non-rotatable but axially displaceable in the actuator housing.
2. Brief Description of the Prior Art
Hydraulic actuators, by which a work station for example a work-bench, a terminal table, sickbed or the like can be raised or lowered for matching to individual requirements, are previously known. In the Swedish Pat. No. 7907974-5 a similar actuator is described with which a number of, for example, four, hydraulic cylinders at the same time can be actuated by means of a hand crank or engine in order to adjust the height of the work station. The actuator in question is made of a pump or a driving unit to which four leg cylinders, that is piston cylinders, are connected by way of flexible tubes, and which are applied in for example a table leg, and by which the table can be raised or lowered. By moving the pistons in the pump unit the pistons in the leg cylinders will be modified on the corresponding way so that the desirable height adjustment is provided. A pump unit for four or several legs is a relatively bulky device, which is often mounted under the table top, where it is easily accessible from the work station. This location results however that the space for the legs under the table is reduced, which is of course a disadvantage. Further for every change in the number of the legs which should be raised or lowered, there must be a special variant, which causes both manufacturing, stock keeping and sevice problems.
Occasionally, an existing system, for example a terminal table, must have an additional side table must have connected and the system must then be completed. With the equipment available today, this is only possible by replacing the old device by new one, which is costly.
The elevation adjustment device for a work station must also be so designed that a heavy uneven loading of the work station will not cause any damage or break-down the actuator.